Measuring the power levels of an operating optical communications system, specifically a passive optical network (“PON”), like those used in fiber to the “X” (X: H=home, C=curb, N=node, P=premises, etc.) configurations, Optical Local Area Networks (“OLANs”), or coarse wavelength division multiplexing (“CWDM”) systems, requires the use of an inline power meter capable of sampling and measuring a small portion of the total optical power of each wavelength present in the optical fiber.
Known methods and apparatus for such power measurement initially tap a portion of the signal, and then separate out the various wavelengths for power measurement thereof. However, these configurations are very complex, and can add loss of signal level at each stage before detection and measurement, limiting the dynamic range of the measurement circuits. Also, these configurations can take up a considerable amount of space inside the instrument designed to measure the optical power levels, adding to the cost of those instruments.
Other known methods and apparatus separate out the wavelengths and then utilize tap photodetectors to sample portions of the signals for power measurement thereof. However, the use of tap photodetectors can, in some cases, be expensive and cumbersome.
Accordingly, improved apparatus for performing optical power measurements is desired.